Project Summary/Abstract Maintaining emotional stability in the face of negative life experiences is critical for healthy aging. Maladaptive responses to negative affective stimuli (?NAffecS?) are implicated in psychiatric disorders, including major depressive disorder (MDD). In fact, there are shared brain regions involved in responses to NAffecS and MDD pathophysiology, including: hypothalamus (HYPO), amygdala (AMYG), hippocampus (HIPP), anterior cingulate cortex (ACC), and ventromedial and orbital prefrontal cortices (vmPFC, OFC), areas that are highly sexually dimorphic. Activity in this circuitry is physiologically associated with cortisol response, loss of parasympathetic cardiac tone, and immune responses, including TNF-?, IL-1?, IL-6, all of which differ by sex. We will test here that immune pathway abnormalities, beginning in fetal development, are associated with sex-dependent impacts on HYPO, HIPP, AMYG and PFC, resulting in maladaptive negative emotion processing and MDD/depressed mood symptomatology in early midlife, the latter of which will accelerate aging of this circuitry and negative emotion dysregulation in later midlife. We are uniquely poised to examine this for the first time in humans using data from our 55-year prospective prenatal cohort followed since 2nd/3rd trimesters of gestation and assessed at ages 44-50 in a previous NIMH study. Over 4 years, we will re-recruit 160 of these offspring who, 11 years later, will be ages 55-61, and relate maternal prenatal immune activity (TNF-?, IL-1?, IL-6, IL-10) to sex differences in midlife NAffec circuitry decline and negative emotion processing dysregulation and the impact of MDD/severe mood symptomatology in early midlife. We will use the same multimodal imaging approach as previously (structural, functional imaging (sMRI/fMRI)) coupled with hormones, autonomic and immune physiology, and emotion regulation measures. Novel transcriptomic analyses in the offspring's peripheral blood mononuclear cells (PBMCs; measuring innate immune gene expression) will be related to adult midlife outcomes. Our lifespan perspective is an innovative approach to identify potential immunotherapeutic targets for maintaining healthy emotion processing that are sex-dependent and can be applied prior to functional decline. This will contribute to RDoC Negative Affect and Arousal phenotypes, physiology and genotypes, and impact of mood and sex.